Optical reader for syringe

ABSTRACT

The present invention relates to a syringe ( 1 ) for use in spectroscopy to identify drugs within the syringe ( 8 ). The syringe comprises a optical window section ( 8 ) either integral with or attached to the syringe ( 1 ). The optical window section ( 8 ) has predetermined physical and optical properties that allows radiation to pass through in a known manner to facilitate spectroscopy.

RELATED/PRIORITY APPLICATION

This application claims priority with respect to New Zealand PatentApplication No. 543876, fled on Nov. 29, 2005.

FIELD OF THE INVENTION

This invention relates to liquid drug delivery devices which prevent orminimise adverse drug advents and in particular though not solely tosyringes adapted for allowing qualitative and/or quantitative monitoringof their contents.

BACKGROUND TO THE INVENTION

Adverse drug events (ADEs) which are caused by the administration to apatient of intravenous medications of incorrect types, concentrations ordosages may cause irreparable damage or even death in a patient. Thesetypes of ADE are entirely preventable and attempts have been made tominimise or avoid their occurrence. An example ADE prevention system isdisclosed in U.S. Pat. No. 6,847,899B. In this document plastic tubingforming part of an TV administration set between an IV bag containing adrug to be administered and a needle in a patient's arm is passedthrough a spectroscopic analyser. The analyser is capable of determiningboth the type of drug present in the tubing and its concentration. Acomparison may be made with expected results from the intended drug typeand concentration and a decision made on whether to allow an infusion tocontinue.

In the above described system, variation in the positioning of thetubing within the spectroscopic analyser and variation in the physicaland optical properties of the tubing itself will affect the outcome ofthe analysis. Furthermore, an IV administration set is often used totransport more than one type of drug, at different times, to thepatient. Contamination of the tubing with multiple drug types reducesthe ability of the spectroscopic analyser to determine the type of drugcurrently present.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide aliquid delivery device and/or optical reader for a liquid deliverydevice which will go at least some way towards overcoming the abovedisadvantages or which will at least provide the industry with a usefulchoice.

In one aspect the present invention may be said to consist in a liquiddelivery device adapted to deliver a liquid drug to a patient or animalcomprising: a reservoir adapted to contain liquid drug to be delivered,the reservoir having an outlet through which liquid drug may bedispensed, a liquid dispenser with a longitudinal axis which causesmovement of the liquid drug from the reservoir to and out of the outlet,the liquid dispenser comprising optically readable markings disposed ata plurality of positions along at least a portion of the longitudinalaxis, an optical reader comprising at least one optical detectorarranged to detect the optically readable markings, each opticaldetector adapted to provide an output signal indicative of one or moredetected optically readable markings, and a processor coupled to receivethe output signal and generate position data indicating a position ofthe liquid dispenser relative to the reservoir.

Preferably the processor generates quantity data indicating a quantityof liquid drug in the reservoir.

Preferably the optically readable markings comprise a plurality ofindicia positioned in a sequence along at least a portion of thelongitudinal axis of the liquid dispenser, and wherein the processorgenerates the position data by counting the number of indicia detectedby the optical detector as the liquid dispenser is moved relative to theoptical detector.

Preferably the optical reader comprises at least two optical detectorsarranged to detect the indicia, wherein the optical detectors arepositioned at a relative separation to provide quadrature encodingsignals that can be used by the processor to generate the position dataand direction data indicating the direction in which the liquiddispenser is moved relative to the optical detector.

Preferably the position data is indicative of the quantity of liquidwithin the reservoir.

Preferably the optical reader comprises a transmitter adapted towirelessly transmit the quantity data or position data to a system.

Preferably the optical reader is detachable from the liquid deliverydevice.

Preferably the optical reader further comprises an energy storage devicecoupled to an inductive device, the inductive device adapted toinductively couple to an inductive recharging device to receive energyfor recharging the energy storage device.

In another aspect the present invention may be said to consist in anoptical reader adapted to couple to a liquid delivery device andgenerate position data indicative of the position of a liquid deliverymeans of the liquid delivery device, the optical reader comprising: acoupling for attachment to a liquid delivery device, at least oneoptical detector arranged to detect optically readable markings on aliquid delivery means, each optical reader adapted to provide an outputsignal indicative of one or more detected optically readable markings,and a processor coupled to receive the output signal and generateposition data indicating a position of the liquid dispenser relative tothe reservoir.

Preferably the processor generates quantity data indicating a quantityof the liquid drug in the reservoir.

Preferably the optically readable markings comprise a plurality ofindicia positioned in a sequence along at least a portion of alongitudinal axis of the liquid dispenser, and wherein the processor cangenerate the position data by counting the number of indicia detected bythe optical detector as the liquid dispenser is moved relative to theoptical detector.

Preferably the optical reader comprises at least two optical detectorsarranged to detect the indicia, wherein the optical detectors arepositioned at a relative separation to provide quadrature encodingsignals that can be used by the processor to generate the position dataand direction data indicating the direction in which the liquiddispenser is moved relative to the optical detector.

Preferably the position data is indicative of a quantity of liquidwithin the reservoir.

Preferably the reader further comprises a transmitter adapted towirelessly transmit the quantity data or position data to a system.

Preferably the optical reader further comprises an energy storage devicecoupled to an inductive device, the inductive device adapted toinductively couple to an inductive recharging device to receive energyfor recharging the energy storage device.

In this specification where reference has been made to patentspecifications, other external documents, or other sources ofinformation, this is generally for the purpose of providing a contextfor discussing the features of the invention. Unless specifically statedotherwise, reference to such external documents is not to be construedas an admission that such documents, or such sources of information, inany jurisdiction, are prior art, or form part of the common generalknowledge in the art The term “comprising” as used in this specificationmeans “consisting at least in part of”. Related terms such as “comprise”and “comprised” are to be interpreted in the same manner.

To those skilled in the art to which the invention relates, many changesin construction and widely differing embodiments and applications of theinvention will suggest themselves without departing from the scope ofthe invention as defined in the appended claims. The disclosures and thedescriptions herein are purely illustrative and are not intended to bein any sense limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a syringe in accordance with a firstembodiment of the invention,

FIG. 2 is a cross-sectional view of the optical window section of thesyringe of FIG. 1 showing its use in reflectance mode spectroscopy,

FIG. 3 is a cross-sectional view of the optical window section of thesyringe of FIG. 1 showing its use in transmission mode spectroscopy,

FIG. 4 is a perspective view of a docking station or sleeve adapted toreceive the syringe of FIG. 1 in order to allow spectroscopic analysison the contents of the syringe to occur,

FIG. 5 is a side elevation of the syringe of FIG. 1 within the dockingstation of FIG. 4,

FIG. 6 is a perspective view of a syringe which also includes amechanism for determining the amount of liquid within the syringe,

FIG. 7 is a schematic block diagram of a spectroscopic analysis systemincluding the syringe of FIGS. 1 and/or 6,

FIG. 8 is a perspective view of a syringe in accordance with a secondembodiment of the invention,

FIGS. 9 a, 9 b are plan views of two optical window sections of thesecond embodiment,

FIGS. 10 a-10 c are various views of the syringe docked in a dockingstation,

FIGS. 11 a, 11 b are plan views of the optical window docked in recessof the docking station,

FIGS. 12 a, 12 b are perspective views of an optical reader adapted forattachment to the syringe,

FIG. 13 is a plan view showing the optical reader attached to thesyringe,

FIG. 14 is a schematic diagram of a qualitative and quantitativeanalysis system incorporating the syringe,

FIGS. 15 a, 15 b show the syringe markings and photodetectors in moredetail,

FIG. 16 is a circuit diagram of one embodiment of the inductive charger,and

FIG. 17 is a circuit diagram of one embodiment of the quadraturedetectors for the optical reader.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Embodiment

With reference to the drawings and in particular FIG. 1, a syringe 1 isshown having a reservoir portion 2 and a liquid dispenser or liquiddispensing means, such as a plunger 3. Although the invention is beingdescribed with reference to a syringe it should be noted that theinvention is equally applicable to other types of liquid deliverydevices which includes a piston and cylinder arrangement such as animaldrench guns or oral dosing systems for animal use.

The syringe's plunger 3 slides within the reservoir 2 as a piston slideswithin a cylinder, to evacuate the contents of the reservoir through anoutlet 4. The outlet may be provided with a needle fitting (not shown)for intravenous delivery of the content of the reservoir to a patient.Alternatively, as shown, an outlet fitting 11 such as a well known “luerlock” or “luer slip” fitting may be provided at the outlet of thereservoir. These fittings allow for twist lock or press fit engagementwith a complimentary fitting on an inlet of a luer forming part of in IVadministration set connected to an indwelling vein access device (suchas a needle or cannula) inserted in a patient. Alternatively, the luermay simply be connected by tubing to a patient's indwelling vein accessdevice (not shown).

As is well known, plunger 3 is provided with a rubber or elastomerichead 5 which is a tight fit within the substantially cylindricallyshaped reservoir 2 and which forms a seal with the inner wall thereof.The end of plunger 3 furthest from the reservoir is provided with aflange 6 adapted to be pressed by a user's thumb whilst the user's firstand second fingers are positioned beneath a flange 7 at the open end ofreservoir 2. In use, as is well known, a user presses flange 6 with hisor her thumb whilst pulling flange 7 with the first and second fingersto cause liquid within the reservoir to be dispensed from outlet 4. Thesyringe may be pre-loaded with liquid or can be filled via the outlet 4in the known way.

Reservoir 2 is preferably transparent or translucent so that a user isable to determine the amount of liquid, such as a liquid drug, heldtherein. Reservoir 2 may be formed from a medical grade plastics orglass material such as HDPE for example. Reservoir 2 includes an opticalwindow section 8 which is preferably formed from a different material tothe remainder of the reservoir 2. The material from which the opticalwindow section 8 is manufactured is a high quality plastics or glasswith close manufacturing tolerances for both its physical and opticalproperties. Suitable exemplary materials from which the optical windowmay be made include cast or extruded Acrylic plastics, Polycarbonateplastics (such as LEXAN® manufactured by GE Plastics), Butyrateplastics, polypropylene and Clear PVC.

In terms of the controlled physical properties, one or more of thethickness, slope and curvature of the optical window section should bewithin predetermined ranges. The material chosen for the optical windowshould have low distortion properties, no or minimal fading, shrinkinglines or optical distortion. Flatness is also important as is theability to reproduce wall thickness and, for use in a transmission modespectroscopic system, wall separation. The wall thickness may range fromabout 0.6 mm to about 1.2 mm and could be 1 mm. The wall separation (thedistance between the wall surface through which light enters and thesurface where affected light enters the sensor opposite) may range fromabout 8 mm to about 12 mm, and preferably around 10 mm Preferably, thepredetermined optical characteristics include the optical density andclarity of the optical window section. Importantly, the material chosenfor the optical window should be substantially transparent with lowabsorbance, preferably a low absorbance particularly in the nearinfra-red range. Polycarbonate plastics may therefore be especiallysuitable.

The optical window section 8 is shown in more detail in FIGS. 2 and 3 inschematic form. The optical window section includes a substantiallycylindrical wall section 9, a transition section 10 and an outletfitting section 11 in which the outlet 4 is formed. Preferably, theentire optical window section 8 is formed from a single homogeneousmaterial which is connected or bonded or sealed to the remaining,open-ended portion of the reservoir 2 during manufacture of thereservoir.

The syringe according to the present invention is adapted to be used inconjunction with a qualitative analysis device such as a spectroscopicanalyser to determine the composition of material within the reservoir2. Accordingly, optical window section 8 is manufactured within knownoptical and physical tolerances so that it has a known affect onradiation passing therethrough. The optical window section 8 willtherefore cause a known reduction in light intensity at knownfrequencies and this effect can be factored in to calculations carriedout by the spectroscopic analyser. The spectroscopic analyser may thendetermine an accurate spectroscopic “fingerprint” of the liquid withinreservoir 2 for comparison with spectroscopic data of known drugs. Inthis way, as a drug is being administered to a patient by the syringe orjust prior to delivery of a drug using the syringe, it is possible tocheck that the drug being delivered is that which is intended to therebyavoid or reduce the risk of an adverse drug event.

As shown in FIG. 2, reflectance mode spectroscopic analysis may becarried out on the syringe by causing light, for example in thenear-infrared (NIR) spectrum, to be incident on the optical windowsection 8. The incident light will be transmitted through the opticalwindow section while being effected by the optical window section in aknown way, interact with the contents within receptacle 2 and then someof the incident light will be reflected back (as shown by the arrows)through the optical window section to a detector having been affected ina known way as it travels back through the optical window section.Incident light is preferably directed at the transition section 10. Thepiston should not be fully depressed as it may interfere with the lightpath through the liquid. The minimum clearance between the end of theplunger and the wall of the transition section of the optical windowdepends upon the choice of plastics or glass material, the width of thelight beam, the angles of incidence and reflection and, in the case of asystem with a lens, the position of the focal point within the syringe.As an example, the minimum clearance may be less than about 5 mm.

Any suitable method of spectroscopic analysis could be used, for examplethe system disclosed in our PCT application published as WO2004/025233A. FTIR (Fourier Transform Infra-Red spectroscopic analysis),Raman scattering, UV/VIS (ultra-violet/visible) and infra-red methodscould also be employed. Some modes of magnetic resonance and low powerradioactive radiation could also be used to determine the composition ofthe liquid within the receptacle.

Alternatively, as shown in FIG. 3, transmission mode spectroscopy couldbe employed to determine the composition of the contents of thereservoir. For example, as shown in FIG. 3, radiation such as light froma radiation source may be directed through the luer fitting 11, thewalls of which will have a known affect on the transmission of theradiation both into and out of the optical window section.

Although not shown, outlet 4 may include a valve to retain liquid in thereceptacle until plunger 3 is pushed. The diameter and roundness of thesubstantially cylindrical outlet fitting section 11 is also manufacturedto strict tolerances and therefore the path length of the radiationtravelling through the contents of the reservoir is accurately knownwhich is of course essential for transmission mode spectroscopicanalysis. In this way, measurements are made repeatable so that usefulcomparisons and/or calibration can be performed. Alternatively, thesubstantially cylindrical outlet fitting section 11 could be providedwith one or more flat sides or could be square or rectangular incross-section. This may however require additional means to orient thesyringe within housing 12 to ensure that the incident light beam isdirected substantially normal to a flattened face of the outlet fitting.

FIG. 4 shows a housing 12 adapted to receive syringe 1 to enablespectroscopic analysis of the syringe's contents to be carried out.Housing 12 forms a substantially cylindrical docking station or holderfor the syringe. Housing 12 has an open first end 13 adapted to receivethe reservoir 2 and a second open end 14 having a smaller openingthrough which outlet fitting 11 may, in use, protrude. Flanges 15 at thefirst end of the housing form a seat for reservoir flanges 7 when thereservoir is positioned appropriately within the housing. An annularconical ring section 15 a forms an optical window in the holder which,in use, is aligned with the transition section 10 of the reservoir'soptical window 8. The physical and optical properties of at least thehousing's optical window section are specified and controlled duringmanufacture in a similar manner to the properties of optical windowsection 8 of reservoir 2.

To enable the combination liquid delivery device (or syringe) andhousing according to the invention to remain as compact and lightweightand as possible, it is preferred that the spectroscopic analyser ispositioned remotely. Accordingly, the spectroscopic analyser 16including radiation source 17 shown in FIG. 4 is connected to housing 12by optical fibres 18 and 19 having terminations 20 and 21 respectivelyon the housing. Terminations 20 and 21 ensure that the ends of thefibres are coupled to the optical window 15 a of the housing to receiveor transmit radiation in appropriate directions. As an example, theincident and reflected beams may have an angle of about 30° betweenthem.

Dependent upon the type of radiation used, other transmission mediumscould be used. Alternatively, the radiation source, such as a lightemitting diode (LED) could be mounted on the housing and controlled viaa wired or wireless connection to the spectrum analyser.

As shown in FIG. 5, housing 12 could be built into a tray or cabinet orother larger fixture. In this case, the spectrum analyser may also bebuilt into that larger fixture. Furthermore, rather than requiringoptical fibres to connect the housing to the spectroscopic analyser,light beams with any necessary lens system could be transmitted throughan air path to and/or from the reservoir.

FIG. 5 also shows a further aspect of the invention wherein the syringeis capable of quantitative analysis of the syringe's contents. This maybe in conjunction with the spectroscopic qualitative analysis describedabove or may be independent thereof. The quantitative analysis isprovided by electrically conductive segments 23 and 24 on reservoir 2.In the example shown where the liquid delivery device constitutes asyringe, conductive segments 23 and 24 may be located substantially onopposite sides of the longitudinal axis of the reservoir extendingaxially substantially the entire length (or a substantial portionthereof) of the reservoir. The conductive segments may be formed aselectrodes from a layer of conductive foil such as aluminium or copper.Alternatively, the conductive layers may be formed from a conductiveplastics material or a plastics material that is doped with a conductiveagent such as graphite or a metallic compound.

The two conductive electrodes form the plates of a capacitor. Thedielectric constant of the material from which the wall(s) of thereservoir are formed or air is significantly different to the dielectricconstant of the (often water-based) liquid drugs inside the reservoir ofthe syringe. As an example, a conventional 10 mL disposable plasticssyringe will change capacitance from a few picofarads to tens ofpicofarads from empty to full of a water-based drug. These amountsobviously depend upon the size of the electrodes and the dimensions ofthe syringe.

Displacement of plunger 3 within reservoir 2 causes liquid within thereservoir to exit via outlet 4. The capacitance of the capacitor formedby the electrodes and air/liquid/plastics material therebetween to varyas a result. It has been found that the capacitance of the capacitorvaries substantially proportionally to the amount of fluid remaininginside the reservoir. By carrying out experiments with various differentliquid drugs, it is possible to develop mathematical relationships or alookup table relating capacitance (or an indicator thereof) and theamount of fluid in the reservoir. Therefore, by simply determining thecapacitance of the capacitor formed by the electrodes printed or appliedto the surface or within the wall of the reservoir, it is possible tocalculate the amount of fluid remaining in the reservoir. During acontinuous time measurement when liquid is being evacuated from thereservoir, the flow rate of the liquid can easily be calculated.

In an alternative (or in addition) to electrodes forming theelectrically conductive segments 23 and 24, coils could be provided oneither side of the reservoir. The coils could be etched onto the sidesof the reservoir or could be provided on adhesive labels for example. Ithas been found that the inductive coupling (or mutual inductance)between the two coils is substantially directly proportional to theamount of liquid remaining in the reservoir.

In either the capacitive or inductive situations, the beat frequency orphase shift of a tuned circuit may be used to determine the capacitanceor inductive coupling between the conductive sections. An electroniccircuit providing a high frequency oscillating voltage or current to anLC resonant tank circuit including the reservoir capacitor or inductorscould be tuned to a particular resonant frequency when the reservoir isempty. The tuned circuit will be de-tuned as a result of the liquidwithin the reservoir and this change in resonant frequency can bedetected and used to calculate capacitance or inductive coupling. Thefrequency or phase shift caused by the change may also be directlyproportional to the amount of liquid between the capacitor plates orcoils. The effect of the liquid on radio frequency transmission from anaerial positioned on the wall of the reservoir could also be used toachieve the same effect. In the case of a capacitive circuit, theelectronic detector circuit may include a circuit that is tuned todetect the charge and/or discharge of an external capacitor formed bythe capacitor plates and the liquid. A regular pulse train of current inthe form of a square wave (of less than 100 kHz for example) may besupplied to the capacitor and the charge and/or discharge time of theunknown capacitor used as an indicator of, or to determine its,capacitance. Alternatively, a comparator circuit could determine thetime taken for the voltage across the unknown capacitor to reach apredetermined value and this could provide an indication of capacitance.

The conductive sections 23 and 24, whether electrodes or coils, requireconductive terminations which could be provided near the top ofreservoir 2. The conductive terminations are connected to an electroniccircuit capable of determining capacitance or inductive coupling or anindication thereof or changes in one of these parameters. Alternatively,raw detected values could be transmitted to a remote device at whichanalysis to determine capacitance or inductive coupling or an indicationof one of these parameters is conducted. The electronic circuit mayinclude an electronic controller executing software which inputs anindication of capacitance or inductive coupling via an analogue todigital converter, analogue comparator or pulse sensing logic circuitfor example. The electronic circuit could conveniently be mounted on orto syringe 1 or housing 12 with connections to the conductiveterminations.

Alternatively, as shown in FIG. 6, a separate housing or sleeve 25 maybe provided about reservoir 2 which houses the electronic sensingcircuit 26 (shown schematically) and includes contacts which mate withthe electrical terminations on the surface of reservoir 2 (circuit 26 isshown connected to conductor section 24 only as conductor section 23 ishidden from view). Note that sleeve 25 has not been shown in FIG. 5 forclarity purposes only. Sleeve 25 may require a power source such as asmall battery and would preferably include a transmitter (and optionallya receiver or transceiver) to allow short range transmission of radiofrequency signals (using the Bluetooth® protocol for example). Sleeve 25may be formed as a ring or torus for example which has an internaldiameter which is a sliding fit about reservoir 2. The reservoir 2 ofthe syringe could then be slid into the ring until the ring reaches itsoperative position with the conductive terminations of the electricalsections 23 and 24 connecting with contacts on the internal surface ofthe ring. The operative position may correspond with sleeve 25contacting flange 7 of the reservoir so that the user may use sleeve 25as finger supports rather than flange 7 during use of the syringe. Oncein the operative position, the sleeve may simply remain there through atight fit or could be bonded or welded into place.

Alternatively, rather than being subsequently mounted to the syringe,sleeve 25 may be formed integrally with the reservoir.

The electronic circuit within sleeve 25 could also include a memorydevice such as an EEPROM (Electrically Erasable Programmable Read-OnlyMemory) for storing data pertinent to the syringe/reservoir and/or theintended content of the syringe. For example, one or more of thefollowing data fields could be stored in the memory device:

-   -   a unique identifier for the syringe/reservoir,    -   an identifier of the type of drug intended to be used with the        syringe,    -   the capacitance or inductive coupling value associated with the        reservoir when empty,    -   the expected capacitance or inductive coupling when the syringe        is fully loaded,    -   calibration information or lookup table(s) to allow detected        capacitance/inductance data to be accurately transformed into a        remaining volume value, and    -   a spectroscopic fingerprint of the expected content of the        reservoir for cross-checking purposes (that is, spectrum data        for comparing with the output from the spectroscopic analyser to        determine whether the composition of syringe's contents is as        expected.

This data or portions of it along with capacitance or inductive couplingdata (or data indicative thereof) could be transmitted to a remotereceiving device connected to a system controller 27 as shown in FIG. 7that executes software instructions. The system controller is connectedto the spectroscopic analyser 16 and an output device such as a display28 unit and/or an audio device such as a speaker 29. System controller27 receives spectrum data from the spectroscopic analyser and maycompare this determined data with stored “fingerprint” data for knownliquid drugs to determine a best match drug. The display unit 28 and/orspeaker 29 may then provide visual and/or audible information to a userof the drug which most closely matches the contents of the reservoir.Alternatively, the display device 28 could output a graphical display ofthe drug's photometric spectrum for review by the user.

If memory device within sleeve 25 is provided with data on the expectedcontent of the syringe or a cross-check fingerprint then this data mayalso be used by the system controller to advise a user whether thedetected drug matches the expected drug characteristics according to thedata held in the syringe. If sleeve 25 included calibration orempty/full capacitance or inductive coupling data then this could beused in the system controller's calculations to determine the amount offluid within the reservoir and a visual and/or audible output of thisparameter could also be provided to the user.

Second Embodiment

FIGS. 8 to 14 show a second embodiment of the invention, which includesamong other things comprises an optical reader for determining thequantity of liquid drug in the syringe and a flat-sided optical window.This embodiment also includes optionally comprises a correspondingdocking station. The second embodiment is utilised in a similar manneras the first embodiment. That is, it can be used to implementqualitative and quantitative analysis of the contents of the syringe.Again, while this embodiment is described with reference to a syringe,it should be noted that the invention is equally applicable to othertypes of liquid delivery devices noted for the first embodiment.

Referring to FIG. 8, the basic syringe 1 is similar to that shown inFIG. 1 and has the same reservoir portion 2 and liquid dispensing meansor plunger 3. The general description of the syringe for the firstembodiment applies for the second embodiment and the details will not berepeated here. The optical window section 80 in the second embodiment isformed as a flat four-sided transparent portion that attaches to or isintegrally formed with the bottom portion of the syringe. The syringe 1also comprises a detachable optical reader 81120. The optical readerdetects markings 82 on the syringe plunger 3 to determine the extent towhich the plunger has been moved., and from this, the quantity of liquidin the syringe can be inferred. The reader 120 comprises electronics (tobe described later) for reading and processing the optical information,and a transceiver for communication the information to a remote system.The optical reader 120 is also fashioned to function as a handle toassist use of the device. Referring briefly to FIGS. 10 a to 10 c, thesyringe is adapted to sit in a holder 100. This enables spectralanalysis of the contents of the syringe.

The syringe, 1 and in particular the window 80 will be described in moredetail with reference to FIG. 8 and the schematic cross-sectiondepiction in FIG. 9 a. The flat-sided window comprises four planartransparent panels 80 a-80 d (of which three are visible in FIG. 8) thatallow for transmission of radiation. The panels are arranged at rightangles to form a receptacle 91 with a square or rectangularcross-section. The panels may be square or rectangular and need not beall the same size. The receptacle 91 can hold a portion of the liquid inthe reservoir and is in fluid communication with it. This enables thedevice to be used in transmission and reflectance spectral analysisequipment. The bottom portion of the window 80 is substantially closedoff (not visible), except for an outlet 94 through which drug expelledfrom the syringe 1 can escape. The window outlet might also comprise, orbe adapted for connection to, a needle 90 or TV administration set (notshown) or other delivery device. The window 80 is formed from a suitableoptical material, the panels 80 a-80 d being joined by a suitable methodor moulded as one piece.

The window 80 of FIGS. 8 and 9 a is formed as part of a separatecomponent 92 that is attachable to an existing syringe 1 and moreparticularly the reservoir 2 of the syringe. The component 92 includes asquare attachment portion 93 extending from the planar window 80, whichhas a larger cross-sectional area. The attachment portion 93 isdimensioned to enable the component 92 to sit over the outlet fitting 11and attach to the bottom of the standard syringe 1 reservoir. Theattachment portion 93 will include an engagement means (not visible)that enables the component 92 to connect to the outlet 11 or other partof the syringe bottom 1 to effect a connection thereto. In a possiblevariation, the attachment portion 92 could be integrally attached to orformed with the syringe 1 reservoir via a suitable moulding or otherprocess. The attachment portion 92 is substantially hollow to allowliquid expelled from the syringe reservoir 2 to pass through to theoutlet 94 in the window bottom and escape the syringe 1 via needle 90.Liquid can also be retained in the receptacle 91 of the window 80 foranalysis purposes. The component 92 could be produced and suppliedindependently from the syringe 1, and would be adapted for use withstandard issue syringes. Preferably there are four planar panelsalthough less are possible. In an alternative embodiment shown in FIG. 9b, there is no attachment portion, but rather the flat-sided window 80is integrally formed with the syringe 1 bottom during the manufacturingprocess of the syringe. A leur 11 is formed at the bottom of the window.The window could be manufactured separately and then moulded to asyringe, or moulded as part of the syringe as a single process, such asan injection moulding process. Preferably, the syringe and window couldbe formed from polypropylene. The advantage of using the same plasticfor the syringe body and the window is that the syringe./window can beformed in a single piece as a single process. This is in contrast towhere the window might be formed as a separate component of a differentplastics, and the welded or otherwise integrated with the syringe body.In this case, the window 80 forms an integral part of the reservoir. Thewindow 80 is effectively formed as part of the syringe 1, with two sidepanel windows “cut-off” to provide parallel window sections. In anotheralternative shown in FIG. 9 c 4four flat panels 80 a-80 d are formed aspart of the bottom of the syringe reservoir 2.

The flat-sided optical window 80 is formed of a suitable material withclose manufacturing tolerances for both its physical and opticalproperties. Suitable materials from which the optical window may be madecomprise cast or extruded Acrylic plastics, Polycarbonate plastics,Butyrate plastics, polypropylene and Clear PVC. The planar nature ofeach side provides a known path for incident radiation, and thethickness of each transparent side is known to ensure it is suitable forthe wavelength radiation being used.

In terms of the controlled physical properties, the thickness of thewindow panels 80 a-80 d should be within predetermined ranges.Preferably, they are 1 mm thick. The material chosen for the opticalwindow should have low distortion properties, no or minimal fading,shrinking lines or optical distortion. Flatness is also important as isthe ability to reproduce wall thickness and, for use in a transmissionmode spectroscopic system, wall separation. The wall thickness may rangefrom about 0.6 mm to about 1.2 mm and preferably 1 mm thick The wallseparation (the distance between the wall surface through which lightenters and the surface where affected light enters the sensor opposite)may range from about 8 mm to about 12 mm, and preferably around 10 mm.Preferably, the predetermined optical characteristics include theoptical density and clarity of the optical window section. Importantly,the material chosen for the optical window should be substantiallytransparent with low absorbance, preferably a low absorbanceparticularly in the near infra-red range. Polycarbonate plastics maytherefore be especially suitable.

Referring now to FIGS. 10 a to 10 c, the syringe 1 with an attached orintegrally formed flat-sided window 80 is adapted for use with a holderor docking station 100. FIG. 10 a shows a perspective view of a syringe1 partially installed in the holder 100, and FIG. 10 b shows in moredetail a syringe 1 being installed. FIG. 10 c shows a plan elevationview of a syringe 1 installed in the holder 100. The holder 100 retainsthe syringe 1 in place, and enables radiation to be directed towards thewindow 80 to enable spectral analysis of the syringe 1 contents. Theholder comprises a base 101, with a docking stand 102 extending from thebase. The stand is preferably angled to assist with convenientoperation. The stand 102 comprises a support portion 103 for supportinga syringe 1 installed in the stand. The stand also includes an internalrecess 110 (shown in FIG. 11 a). The recess is shaped and dimensioned toreceive the flat-sided window 80 attached to the syringe. Onceinstalled, the window 80 is retained in the recess 110 and the reservoir2 of the syringe 1 rests against the support 103. The stand furthercomprises a second internal recess (not visible) extending from thefirst recess 110 towards the base 101 adapted to receive a needleattached to the window 80. The docking stand 102 might also include awindow, aperture or other viewing portion to enable the user to view thedocking process. This window shows a spring loaded reference tile 104.When the syringe is not in the docking station, the spring pushes areference tile into the light path. When the syringe is in the holder,the reference tile is displaced and the sample under investigation canbe optically analysed.

The stand 102 has two optical terminations 105 a, 105 b positioned onthe outer walls of the stand either side of the internal recess 110.Each termination 105 a, 105 b is adapted for coupling to a fibre opticcable or other optical transmission means by way of a screw mechanism orsimilar. Each termination also has an internal aperture 113 or otheroptical transmission means that extends through the termination andthrough the exterior wall of the stand adjacent the recess to provide anoptical path 111 (e.g. see FIG. 11 a) to the recess 110. By coupling afibre optic cable or the like to a termination 105 a, 105 b, radiationcan be transmitted into the recess 110. When a flat-sided window 80 isin the recess 110, this radiation 111 will be transferred through thewindow 80 into the liquid inside. Likewise, radiation 112 coming fromthe recess can be received at an external sensor coupled to thetermination 105 a.

FIG. 11 a is a top cross-sectional view showing the flat-sided window 80of the syringe 1 positioned snugly in the recess 110 of the holder 100.In particular, the tight fit and square shape prevents rotationalmovement of the syringe. As noted earlier, the window 80 could be formedwith a rectangular shaped cross-section. The known properties of theflat-sided window, along with its secure retention to reduce the risk ofrotation provides more certainty in the optical parameters. As rotationof the window in the holder is prevented, or at least reduced, theincident radiation path 111 will be known along with the knownproperties of the window 80, which provides for a more accuratedetermination of the contents of the liquid drug. Preferably, theincident path 111 of radiation incident on the window panel 80 cb fromthe termination 105 b will be normal to the face of the window panel 80cb. Similarly, radiation 112 transmitted through or reflected fromliquid in the window 80 will travel normally through the window panel 80bc and to the receiving termination 105 a.

Referring to FIG. 11 b, in a further embodiment, the flat-sided opticalwindow 80 might include rails, engagement portions or other protrusions115 a-115 d, which engage with a corresponding channel 116 a-116 d orthe like in the holder 100. This further assists in retaining theinstalled syringe 1 in a fixed rotational position. It also assists withinsertion and location of the window 80 into the recess in the correctorientation.

Referring to FIG. 9 b, the plunger, which is provided with a rubber orelastomeric bead 5, also preferably comprises an extension portion 95.The extension portion is profiled to slide with a tight fit into thewindow portion 80 when the plunger 6 is pushed downwards as shown inFIG. 9 b. This ensures any liquid that resides in the window portion 80receptacle 91 is expelled through the outlet 94 upon actuating thesyringe. While the extension portion 95 is not essential, it preventswastage of liquid which might remain in the window portion 80 by use ofa standard plunger head. FIG. 9 c shows the plunger such that theextension is retracted from the receptacle 91.

The syringe 1 is also adapted to be used with a detachable opticalreader 120 for determining the quantity of liquid drug within thereservoir 2, as shown in FIGS. 12 a to 13 FIG. 12 a shows the reader 120detached from the syringe 1, while FIG. 12 b shows the reader 120attached. The optical reader comprises a body portion 121 for retainingthe required electronics for optical reading and clip means 122 a-124 bfor attaching the optical reader 120 to the reservoir. The middle clips123 a, 123 b are resilient and engage around the circumference of thereservoir below the flange 7. The top clips 124 a, 124 b sit above theflange 7 and resiliently clip around the cross arms of the plunger 6(visible in FIG. 13). Similarly, the bottom clips 122 a, 122 bresiliently engage with the reservoir 2 further down its length. Thereader 120 also comprises preferably two optical receivers 140 (one ofwhich is visible in FIG. 13, the other is directly underneath and notvisible), which might be photodiodes or similar. The plunger 63 isformed as a cross-shaped extrusion as shown in FIG. 13. The flange 6 isremoved from FIG. 13 for clarity.

The plunger 3 comprises optically readable markings 82 on the flat faceof at least one arm of the cross 131 d (see e.g. FIG. 8). The opticallyreadable markings 82 are preferably a plurality of markings positionedat least partially along the longitudinal length of the arm 131 d. Theknown spacing or arrangement of the markings allow the position and/ordirection of the plunger 3 to be determined. Preferably the markings arelinearly arrange black bars 82. Alternatively, other types of opticallyreadable markings can be used. The photodetectors e.g. 140 are arrangedon the reader so they can detect the optical markings 82 on the plunger3.

The markings 125 can be used to determine linear movement of theplunger. As the plunger 3 is moved downwards within the reservoir 2, theoptical detectors 140 detect the bars on the plunger. The opticaldetectors detect each bar and feed this information into theelectronics, which can count the number of bars to determine theposition of the plunger 3 and thereby infer how far the plunger 3 hasmoved within the reservoir 2. The processor of the electronicsdetermines position data from this. This in turn indicates the quantityof liquid drug remaining within the reservoir 2. That is, thelongitudinal positional movement of the plunger 3 within the reservoir 2defines a cavity in the reservoir for liquid. Therefore assuming thereis no air space in that cavity, once the position of the plunger in itslongitudinal position within the reservoir is known, the size of thecavity can be determined and therefore the amount of liquid therein.Therefore by counting the number of black bars that have passed thedetectors, the longitudinal movement in the reservoir can be known. Thisworks in both directions, therefore if the plunger is retracted back toincrease the cavity size, by counting the number of bars the amount ofretraction is known and therefore the cavity size and the amount ofliquid.

To enable determining the size of the cavity based on movement of theplunger 3 in both directions, two optical detectors are provided asshown in FIG. 15 a, 15 b. The use of two optical detectors enablesquadrature encoding to allow the absolute position and direction of theplunger 3 movement to be determined. The use of quadrature encoding willbe described in relation to FIG. 15 a, and 15 b. A possible embodimentfor the circuits of the quadrature detector are shown in FIG. 17 TheseFigures shown two spaced apart photodetectors 140 a, 140 b whichindividually can detect black bars on the plunger 3 and feed thisinformation to the electronics, including the processor. From this thenumber of bars that have passed a detector can be counted and movementlongitudinally of the plunger determined as described previously.Together the two photodetectors also provide information on whichdirection the plunger is moving.

As shown in FIG. 15 a the first photodetector 140 a is situated in aposition such that it detects bar 160 The second photodetector 140 b isin a position where it does not detect a bar. It should be noted thatthe photodetectors have to be spaced apart a different distance in thespacing between the bars such that the photodetectors do not detect barsor at least the edges of bars simultaneously. Next, as shown in FIG. 15b the plunger 3 has been moved such that bar 160 is now detected by thesecond photodetector 140 b. At this point the first photodetector 140 adoes not detect any bar. Because the first photodetector 140 a detecteda bar and then second photodetector 140 b detected a bar subsequently,(prior to photodetector a detecting any other bar) the electronics caninfer that the direction of movement of the plunger is downwards asshown by the arrow 161. It can therefore know that as each detectordetects a bar this means the volume of the cavity is decreasing by anamount proportional to the distance between the bars. Each time anotherbar is detected in this manner again the electronics can infer that thesize of the cavity and the amount of liquid has again decreased byamount proportional to the distance between the bars. Those skilled inthe art will know that the cavity size will be related to the diameterof the syringe and the distance between the bottom of the plunger 5 andthe bottom of the syringe reservoir 2. The distance between the bottomof the plunger and the bottom of the syringe reservoir will be relatedto the movement of the syringe in the reservoir and therefore theposition of the bars as they move past the detectors.

Similarly, quadrature encoding can determine when the syringe is movingin the opposite direction. When the syringe has moved upwards, thephotodetectors 140 a, 140 b can detect the direction of movement and thenumber of bars they transverse indicates the increase in the size of thecavity between the bottom of the plunger and the bottom of the syringereservoir. In turn this indicates the amount of liquid in the cavity ifliquid is being drawn into the syringe through the needle.

The use of quantity analysis in this manner enables the quantity ofliquid in the syringe to be determined when the syringe is actuallybeing actuated. It is not necessary for the syringe to be installed in aholder. Therefore the syringe can provide continuous and real-timemeasurements of the quantity of liquid in the syringe.

The optical reader 120 can either be hard wired or preferably wirelesslyconnected to the spectral analyser to relay the quantity information.The optical reader 120 can also be attached and detached from thereservoir 2 as required. Other forms of optical markings and processingcould be used to determine the extent that the plunger 3 has moved.

The optical reader 120 is moulded to also act as a holder to enable aperson to use the device, for example as shown in FIG. 8. The reader 120also comprises clip means 130 a-130 d extending from the upper resilientclips 124 a, 124 b as shown in FIG. 13. The clip means 130 a-130 dextend from the upper resilient arms 124 a, 124 b and engage with one ormore of the flat arms 131 a-131 d of the extruded plunger 3. By doing sothe clip means restricts rotational movement of the plunger 3, andallows the plunger to solely move in a linear manner. This ensures thatthe squared profiled plunger 95 extension portion will be receivedproperly into the internal portion of the window 80 when the plunger 3is forced downwards. Any rotation of the plunger 3 might prevent theplunger extension portion 95 extending into the window 80 and thereforeprevent all liquid being expelled from the syringe 1. Alternatively, aflip disc that is hingeably connected to the syringe and that hasopenings corresponding to the cross arms of the plunger could be used.To prevent rotation of the plunger, the flip disc could be flipped aboutits hinge and snap locked onto the top of the plunger. This will preventrotation but still allow longitudinal movement of the plunger.

FIG. 14 shows a block diagram of the electronics in the optical reader120. The photodetectors 140 a, 140 b, which are position on the clips124 a, 124 b to detect the plunger markings 125, are connected to aprocessor 141. This could be a microprocessor, microcontroller orsimilar. The processor 141 receives information on the markings from thedetectors 140, and from this determines the position of the plunger 3within the reservoir 2 and the direction of movement. From this, theliquid quantity in the reservoir 2 can be inferred by the processor 141,or other system The processor 141 is connected to a wireless transceiver142 to transmit the quantitative analysis information (or informationfrom which this analysis can be performed) to a computer system 151 viaa transceiver 143, where the information can be used as required. Thewireless transceiver 141 can any suitable type, such as an optical orradio (e.g. RF) transceiver. The electronics also comprises a battery149 for powering the electronics, and an inductive coupler (150 a inFIG. 14, 180 in FIG. 12 b) for coupling the battery to an externalinductive charging means (150 b in FIG. 14, 181 in FIG. 12 b). Thesecondary circuit of the inductive charger 180 is shown in FIG. 16. Asshown in FIGS. 10 b and 12 b, the optical reader has an inductivecharger coil 180 extending therefrom. When the syringe engages in thedocking station as shown in FIG. 10 b, the charger coil 180 extendingfrom the reader will engage, abut or otherwise couple to the inductivecharger coil 181 on the docking station to allow for inductive couplingand charging of the battery.

FIG. 14 shows in schematic form the overall system and indicates itsoverall functionality. The system is adapted for use with the syringe asdescribed previously. The optical reader 120 with the photodetectors 140a, 140 b is adapted for connection to the syringe. The opticalquantitative analysis information it reads from the syringe 1 isprocessed and then the information sent to the computer system 151 viathe wireless link transceiver 142. The processor 141 can process theoptical information to infer quantitative analysis, or otherwise provideraw information which is then processed by the computer system 143151(preferably located separated from the holder 100 and syringe 1). Thesystem also includes the holder 100 for receiving the syringe 1. Theholder includes a light source 146 for directing incident radiation ontothe drug in the window of the installed syringe, and a sensor 145 (twoalternatives shown) for sensing the received radiation that has beenaffected by the drug in the window. Alternatively, the light source andsensor are remotely positioned, and the light transferred to the holderusing a suitable means. The sensed information is then transmitted,preferably wirelessly, via the transceiver 142 to the spectrum analyser147 of the computer system 151. The spectrum analyser 147 determines thedrug type from the spectral analysis information received from thesensor 145. A system controller 144 is connected to the analyser 147 andan audio device such as a speaker 148 a and a display unit 148 b. Thesystem controller 147 receives spectrum data from the spectroscopicanalyser and may compare this to stored “fingerprint” data from knownliquid drugs to determine a best match drug. The display unit 148 band/or speaker 148 a may then provide visual and/or audible informationto a user of the drug which most closely matches the contents of thereservoir. Alternatively, the display device 148 a could output agraphical display of the drugs liquid's photometric spectrum for reviewby the user. The system controller 144 also receives the quantityinformation and advises the user accordingly, and provides any alerts orwarnings regarding the quantity of drug in the reservoir, or thequantity of drug administered to a patient. It will be appreciated bythose skilled in the art that the quantitative and qualitative analysisinformation received from the holder 100 and optical reader 120 could beused in numerous ways to provide various checks and information to theuser.

A method of use of the invention will now be described with reference toFIGS. 8 and 10 a. Referring to FIG. 10 a, the medic will first fill thereservoir 2 of the syringe 1 with the desired drug or other liquid andthen position the plunger 3 so that it contains the correct quantity ofthe drug in accordance with the human readable markings 153 on the sideof the syringe 1. The medic ensures that a portion of the drug sitswithin the window 80 of the syringe. The syringe is then docked into thedocking station 100 by inserting the window 80 into the recess 110 andresting the cylinder of the syringe 1 on the support 103. If not donealready, the terminations 105 a, 105 b of the holder 120 will beconnected to an incident radiation source and an optical sensorrespectively (shown schematically in FIG. 14). The optical sensor 145may be hard wired directly to the spectrum analyser 147 and computersystem or alternatively the information can be transmitted wirelessly tosuch a system. Alternatively, the affected radiation leaving the sampleunder observation might be optically transmitted to the spectrumanalyser 147 either through fibre optic cable or wirelessly.

When the syringe 1 is installed, the drug within the window 80 will sitin the recess 110 within the optical path of the source radiation 146.The analyser system 147 can then be activated and a spectral readingtaken from the incident radiation on the drug within the window 80. Thiscan be processed in the usual way and the medic advised as necessary.Simultaneously, or at another suitable time the optical reader 120 isactivated to read the markings 82 on the plunger of the syringe in orderto determine quantitatively the amount of liquid within the syringe 1.This can be done in real-time such that a continuous or periodicquantity reading can be made as the plunger is moved. This is alsotransmitted wirelessly to the computer system 151 a which uses theinformation and provides any warnings or advice to the medic asrequired. When the qualitative and quantitative analysis has been made,the medic can then remove the syringe 1 from the docking station 100.Note, the syringe does not have to be in the holder to take a quantityreading. The medic can then administer the drug to a patient by holdingthe device I as shown in FIG. 8 and pressing on the plunger 3 to expelthe liquid from the syringe 1.

FIG. 8 shows the syringe in use. The user can attach the optical reader120 to the reservoir 2 and then hold the syringe 1 by placing theirforefinger under the curved surface of the bottom of the optical reader120 and placing their thumb on the top 6 of the plunger 3. They can theninject the contents from the syringe 1 by pressing on the plunger 3 withtheir thumb in the usual manner. The plunger 3 will move downwards intothe reservoir 2 and in doing so the optical markings 125 on the plunger3 will pass the optical receptors 140 in the reader 120. As the markings82 pass the optical receptors 140 a, 140 b the markings 82 are detectedand the information passed to the processor 141, which determines thedirection and extent of movement of the plunger 3 within the reservoir2. This information can then be used to determine the quantity of liquiddrug within the syringe as mentioned previously. This information can beused in any desired manner, such as providing a warning when too littleor too much of a drug has been dispensed or providing any other usefulinformation.

As noted, the syringe is adapted to be used in conjunction with aqualitative analysis device such as the spectroscopic analyser 147 todetermine the composition of material within the reservoir. Accordingly,optical window 8 is manufactured within known optical and physicaltolerances so that it has a known affect on radiation passingtherethrough. The optical window section 80 will therefore cause a knownreduction in light intensity at known frequencies and this effect can befactored in to calculations carried out by the spectroscopic analyser147. The spectroscopic analyser may then determine an accuratespectroscopic “fingerprint” of the liquid within reservoir forcomparison with spectroscopic data of known drugs. In this way, as adrug is being administered to a patient by the syringe or just prior todelivery of a drug using the syringe, it is possible to check that thedrug being delivered is that which is intended to thereby avoid orreduce the risk of an adverse drug event.

Reflectance mode spectroscopic analysis may be carried out on thesyringe by causing light, for example in the near-infrared (NIR)spectrum, to be incident on the optical window section 80. The incidentlight will be transmitted through the optical window section while beingeffected by the optical window section in a known way, interact with thecontents within receptacle and then some of the incident light will bereflected back through the optical window section to a detector havingbeen affected in a known way as it travels back through the opticalwindow section.

Any suitable method of spectroscopic analysis could be used, for examplethose mentioned in relation to the first embodiment.

Alternatively, transmission mode spectroscopy could be employed todetermine the composition of the contents of the reservoir.

While this is preferred a preferred embodiment, alternatives arepossible. It will be appreciated that the window could comprise morethan four panels (e.g., have hexagonal, octagonal profiles or the like),or the window could comprise less that four panels, such as three. Onepossibility is that the window could have one or two planar panels, withthe remainder being formed as a circular shape, or some other non-planarshape. In such an embodiment, the recess in the stand would be shapedaccordingly to receive the window, and the plunger extension as shapedaccordingly.

The present invention provides a low cost and disposable liquid deliverydevice (such as a syringe) and associated spectroscopic system whichenables a user to determine, at a patient's bedside whether a drug whichis about to be injected is what is intended. As the syringe isdisposable, it will only ever hold a single type of liquid and will nottherefore suffer from contamination which could otherwise skewspectroscopic analysis results. The syringe is also advantageouslyportable and could even be utilised (to dispense liquids) whilst locatedwithin housing 12.

1. A liquid delivery device adapted to deliver a liquid drug to apatient or animal comprising: a reservoir adapted to contain liquid drugto be delivered, the reservoir having an outlet through which liquiddrug may be dispensed, a liquid dispenser with a longitudinal axis whichcauses movement of the liquid drug from the reservoir to and out of theoutlet, the liquid dispenser comprising optically readable markingsdisposed at a plurality of positions along at least a portion of thelongitudinal axis, an optical reader comprising at least one opticaldetector arranged to detect the optically readable markings, eachoptical detector adapted to provide an output signal indicative of oneor more detected optically readable markings, and a processor coupled toreceive the output signal and generate position data indicating aposition of the liquid dispenser relative to the reservoir.
 2. A liquiddelivery device according to claim 1 wherein the processor generatesquantity data indicating a quantity of liquid drug in the reservoir. 3.A liquid delivery device according to claim 1 wherein the opticallyreadable markings comprise a plurality of indicia positioned in asequence along at least a portion of the longitudinal axis of the liquiddispenser, and wherein the processor generates the position data bycounting the number of indicia detected by the optical detector as theliquid dispenser is moved relative to the optical detector.
 4. A liquiddelivery device according to claim 3 wherein the optical readercomprises at least two optical detectors arranged to detect the indicia,wherein the optical detectors are positioned at a relative separation toprovide quadrature encoding signals that can be used by the processor togenerate the position data and direction data indicating the directionin which the liquid dispenser is moved relative to the optical detector.5. A liquid delivery device according to claim 3 wherein the positiondata is indicative of the quantity of liquid within the reservoir.
 6. Aliquid delivery device according to claim 3 wherein the optical readercomprises a transmitter adapted to wirelessly transmit the quantity dataor position data to a system.
 7. A liquid delivery device according toclaim 3 wherein the optical reader is detachable from the liquiddelivery device.
 8. A liquid delivery device according to claim 3wherein the optical reader further comprises an energy storage devicecoupled to an inductive device, the inductive device adapted toinductively couple to an inductive recharging device to receive energyfor recharging the energy storage device.
 9. An optical reader adaptedto couple to a liquid delivery device and generate position dataindicative of the position of a liquid delivery means of the liquiddelivery device, the optical reader comprising: a coupling forattachment to a liquid delivery device, at least one optical detectorarranged to detect optically readable markings on a liquid deliverymeans, each optical reader adapted to provide an output signalindicative of one or more detected optically readable markings, and aprocessor coupled to receive the output signal and generate positiondata indicating a position of the liquid dispenser relative to thereservoir.
 10. An optical reader according to claim 9 wherein theprocessor generates quantity data indicating a quantity of the liquiddrug in the reservoir.
 11. An optical reader according to claim 9wherein the optically readable markings comprise a plurality of indiciapositioned in a sequence along at least a portion of a longitudinal axisof the liquid dispenser, and wherein the processor can generate theposition data by counting the number of indicia detected by the opticaldetector as the liquid dispenser is moved relative to the opticaldetector.
 12. An optical reader according to claim 9 wherein the opticalreader comprises at least two optical detectors arranged to detect theindicia, wherein the optical detectors are positioned at a relativeseparation to provide quadrature encoding signals that can be used bythe processor to generate the position data and direction dataindicating the direction in which the liquid dispenser is moved relativeto the optical detector.
 13. An optical reader according to claim 9wherein the position data is indicative of a quantity of liquid withinthe reservoir.
 14. An optical reader according to claim 10 furthercomprising a transmitter adapted to wirelessly transmit the quantitydata or position data to a system.
 15. An optical reader according toclaim 9 wherein the optical reader further comprises an energy storagedevice coupled to an inductive device, the inductive device adapted toinductively couple to an inductive recharging device to receive energyfor recharging the energy storage device.